I would wonder the need for that control structure. You would do better to run code that would not take processor time while blocking the Thread. For example:
1) Using threadA.join();
2) Using wait()/notify()
3) Using java.util.concurrent.Lock/Condition (if they are available on J2ME, not sure if they are).

The point is that the while (boolean) {} loop is processor intensive. It must continue to run, taking processor time away from the other tasks you really want to run. This makes your entire application run slower. These other methods would put the Thread into a waiting state which does not use any processor time until they are woken up from an external source (such as the other Thread).